Biostimulator header assembly having integrated antenna

ABSTRACT

A biostimulator, such as a leadless cardiac pacemaker, having a header assembly that includes an antenna, is described. The antenna can be integrated into an insulator that separates an electrode of the header assembly from a flange of the header assembly. The antenna includes an antenna loop embedded in a ceramic material of the insulator. The antenna loop is located distal to the flange to reduce the likelihood of signal interference and increase communication range of the antenna. The header assembly is mounted on a housing have an electronics compartment, and an antenna lead extends from the antenna loop to electronic circuitry contained within the electronics compartment. Other embodiments are also described and claimed.

This application claims the benefit of priority to U.S. ProvisionalPatent Application No. 62/949,996 entitled “BIOSTIMULATOR HEADERASSEMBLY HAVING INTEGRATED ANTENNA” filed on Dec. 18, 2019, and thatpatent application is incorporated herein in its entirety.

BACKGROUND Field

The present disclosure relates to biostimulators. More specifically, thepresent disclosure relates to leadless biostimulators having headerassemblies.

Background Information

Cardiac pacing by an artificial pacemaker provides an electricalstimulation to the heart when its own natural pacemaker and/orconduction system fails to provide synchronized atrial and ventricularcontractions at rates and intervals sufficient for a patient's health.Such antibradycardial pacing provides relief from symptoms and even lifesupport for hundreds of thousands of patients. Cardiac pacing may alsoprovide electrical overdrive stimulation to suppress or converttachyarrhythmias, again supplying relief from symptoms and preventing orterminating arrhythmias that could lead to sudden cardiac death.

Cardiac pacing by currently available or conventional pacemakers isusually performed by a pulse generator implanted subcutaneously orsub-muscularly in or near a patient's pectoral region. Pulse generatorparameters are usually interrogated and modified by a programming deviceoutside the body, via a loosely-coupled transformer with one inductancewithin the body and another outside, or via electromagnetic radiationwith one antenna within the body and another outside. The generatorusually connects to the proximal end of one or more implanted leads, thedistal end of which contains one or more electrodes for positioningadjacent to the inside or outside wall of a cardiac chamber. The leadshave an insulated electrical conductor or conductors for connecting thepulse generator to electrodes in the heart.

Conventional pacemakers have several drawbacks, including complexconnections between the leads and the pulse generator, and a risk ofinfection and morbidity due to the separate leads and pulse generatorcomponents. Self-contained and self-sustainable biostimulators, orso-called leadless biostimulators, have been developed to address suchdrawbacks. A leadless biostimulator has no connections between the pulsegenerator and a lead. Furthermore, the leadless biostimulator can beattached to tissue within a dynamic environment, e.g., within a chamberof a beating heart, with reduced likelihood of infection. Accordingly,leadless biostimulator technology represents the latest advancement inpacemaker technology. The leadless biostimulator can interact with thetissue using a header assembly, which typically includes a fixationmechanism to attach to the tissue and an electrical feedthrough todeliver electrical impulses from the pulse generator to the tissue.

SUMMARY

Existing leadless biostimulators could benefit from the ability tocommunicate data, such as performance information, from the implantedbiostimulator to a device external to the patient. To enable suchcommunication, an antenna can be integrated into the leadlessbiostimulator. It may be undesirable, however, to integrate the antennaif it requires an increase in a size of the biostimulator. For example,the antenna may require an increase to the size of a biostimulatorhousing, which may negatively impact device implantation and/orperformance. Compactness of implantable devices is paramount, and thus,there is a need to integrate the antenna within the biostimulatorwithout changing the form factor of the biostimulator.

A biostimulator having an antenna to wirelessly communicate signals isprovided. The antenna is integrated into an insulator of a headerassembly, and thus, does not require enlargement of the biostimulatorform factor. The insulator can include, for example, a ceramic material,and the antenna can be a monopole antenna embedded within the ceramicmaterial.

The biostimulator can include a housing having an electronicscompartment, and the header assembly can be mounted on the housing. Moreparticularly, the header assembly can include a flange, and the flangecan be mounted on the housing to enclose the electronics compartment.Electronic circuitry, such as communication circuitry, can be locatedwithin the electronics compartment. In an embodiment, the antenna has anantenna lead that connects to the electronic circuitry. The antenna canbe embedded within the insulator of the header assembly, and thus, theantenna lead can extend from the electronic circuitry contained withinthe electronics compartment through the insulator to one or more antennaloops.

In an embodiment, the insulator includes an insulator wall extendingaround an insulator cavity. The insulator cavity extends along alongitudinal axis from an insulator distal end of the insulator wall toan insulator proximal end of the insulator wall. An electrode of theheader assembly can be disposed within the insulator cavity. The antennahas one or more antenna loops embedded in the insulator wall between theinsulator distal end and the insulator proximal end. Thus, the antennaloop(s) can extend around the electrode. The antenna loop(s) can includeone or more open loops. For example, the one or more open loops caninclude several open loops extending around the longitudinal axis. In anembodiment, one or more of the antenna loop(s) are located distal to theflange of the header assembly, and thus, the flange does not interferewith communication by the antenna loop(s).

In an embodiment, the header assembly includes a helix mount mounted onthe flange. The header assembly can also include a gasket. The gasketcan have an annular body extending around the electrode. The annularbody may be resiliently compressed between the helix mount and one ofthe flange or the insulator. In an embodiment, the gasket is resilientlycompressed between the helix mount and the flange. In an embodiment, thegasket is resiliently compressed between the helix mount and theinsulator. The gasket prevents liquid ingress that could interfere withdevice function.

In an embodiment, a distal section of the insulator wall of theinsulator has a first transverse width larger than a second transversewidth of a proximal section of the insulator wall. The antenna loop(s)can be embedded within the distal section, which can be located distalto the flange. The antenna lead can run through the proximal section,which can be located radially inward from the flange. Accordingly, theantenna lead can carry signals through the proximal section to theantenna loop(s) in the distal section for transmission.

The above summary does not include an exhaustive list of all aspects ofthe present invention. It is contemplated that the invention includesall systems and methods that can be practiced from all suitablecombinations of the various aspects summarized above, as well as thosedisclosed in the Detailed Description below and particularly pointed outin the claims filed with the application. Such combinations haveparticular advantages not specifically recited in the above summary.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features of the invention are set forth with particularity inthe claims that follow. A better understanding of the features andadvantages of the present invention will be obtained by reference to thefollowing detailed description that sets forth illustrative embodiments,in which the principles of the invention are utilized, and theaccompanying drawings of which:

FIG. 1 is a perspective view of a biostimulator, in accordance with anembodiment.

FIG. 2 is an exploded view of a biostimulator, in accordance with anembodiment.

FIG. 3 is a perspective view of a feedthrough subassembly of a headerassembly of a biostimulator, in accordance with an embodiment.

FIG. 4 is an exploded view of a feedthrough subassembly of a headerassembly of a biostimulator, in accordance with an embodiment.

FIG. 5 is a cross-sectional view of a header assembly of abiostimulator, in accordance with an embodiment.

FIG. 6 is a perspective view of an insulator for a header assembly of abiostimulator, in accordance with an embodiment.

FIG. 7 is a cross-sectional view of a header assembly of abiostimulator, in accordance with an embodiment.

FIG. 8 is a perspective view of an insulator for a header assembly of abiostimulator, in accordance with an embodiment.

DETAILED DESCRIPTION

Embodiments describe a biostimulator, e.g., a leadless pacemaker, havinga header assembly that includes an antenna. The biostimulator may beused to pace cardiac tissue. Alternatively, the biostimulator may beused in other applications, such as deep brain stimulation. Thus,reference to the biostimulator as being a leadless cardiac pacemaker isnot limiting.

In various embodiments, description is made with reference to thefigures. However, certain embodiments may be practiced without one ormore of these specific details, or in combination with other knownmethods and configurations. In the following description, numerousspecific details are set forth, such as specific configurations,dimensions, and processes, in order to provide a thorough understandingof the embodiments. In other instances, well-known processes andmanufacturing techniques have not been described in particular detail inorder to not unnecessarily obscure the description. Reference throughoutthis specification to “one embodiment,” “an embodiment,” or the like,means that a particular feature, structure, configuration, orcharacteristic described is included in at least one embodiment. Thus,the appearance of the phrase “one embodiment,” “an embodiment,” or thelike, in various places throughout this specification are notnecessarily referring to the same embodiment. Furthermore, theparticular features, structures, configurations, or characteristics maybe combined in any suitable manner in one or more embodiments.

The use of relative terms throughout the description may denote arelative position or direction. For example, “distal” may indicate afirst direction along a longitudinal axis of a biostimulator. Similarly,“proximal” may indicate a second direction opposite to the firstdirection. Such terms are provided to establish relative frames ofreference, however, and are not intended to limit the use or orientationof a biostimulator to a specific configuration described in the variousembodiments below.

In an aspect, a biostimulator such as a leadless cardiac pacemaker isprovided. The biostimulator includes an antenna integrated into a headerassembly. More particularly, the antenna can be integrated into afeedthrough subassembly of the header assembly, e.g., by embedding theantenna within an insulator of the subassembly. Embedding the antennawithin a ceramic material of the insulator allows integration of theantenna without increasing a form factor of the biostimulator. Theinsulator can separate a flange of the biostimulator from an electrodeof the biostimulator, and at least a portion of the insulator can extenddistal to the flange. Accordingly, the antenna can include one or moreloops, e.g., open loops, embedded within the insulator distal to theflange. Positioning the one or more loops distal to the flange canreduce signal interference from the flange, which may increase acommunication range of the antenna. The header assembly may include agasket to prevent ingress of fluid into an internal volume of thebiostimulator, and the gasket may be located outside of or inside of theinsulator.

Referring to FIG. 1 , a perspective view of a biostimulator is shown inaccordance with an embodiment. A biostimulator 100 can be a leadlessbiostimulator, e.g., a leadless cardiac pacemaker. The biostimulator 100can include an electrode 104 at a distal end of the device, and aproximal electrode 106 proximal to the electrode 104. The electrodes canbe integral to a housing 102, or connected to the housing, e.g., at adistance of less than several centimeters from the housing 102. Thehousing 102 can contain an energy source to provide power to the pacingelectrodes. The energy source can be a battery, such as a lithium carbonmonofluoride (CFx) cell, or a hybrid battery, such as a combined CFx andsilver vanadium oxide (SVO/CFx) mixed-chemistry cell. Similarly, theenergy source can be an ultracapacitor. In an embodiment, the energysource can be an energy harvesting device, such as a piezoelectricdevice that converts mechanical strain into electrical current orvoltage. The energy source can also be an ultrasound transmitter thatuses ultrasound technology to transfer energy from an ultrasoundsubcutaneous pulse generator to a receiver-electrode implanted on anendocardial wall.

The biostimulator 100 can have a longitudinal axis 108. The longitudinalaxis 108 can be an axis of symmetry, along which several biostimulatorcomponents are disposed. For example, a header assembly 110 can bemounted on a distal end of the housing 102 along the longitudinal axis108. The header assembly 110 can include an electrical feedthroughsubassembly including an electrical feedthrough (not shown) and theelectrode 104, e.g., a pacing tip. The header assembly 110 can alsoinclude a fixation subassembly. The fixation subassembly can include ahelix mount 112. The helix mount 112 can be mounted on the electricalfeedthrough subassembly around the longitudinal axis 108. In anembodiment, the fixation subassembly includes a fixation element 114mounted on the helix mount 112 along the longitudinal axis 108. Theassembled components of the biostimulator 100 can provide a distalregion that attaches to a target tissue, e.g., via engagement of thefixation element 114 with the target tissue. The distal region candeliver a pacing impulse to the target tissue, e.g., via the distalelectrode 104 that is held against the target tissue.

Referring to FIG. 2 , an exploded view of a biostimulator is shown inaccordance with an embodiment. The housing 102 can contain anelectronics compartment 116. More particularly, the housing 102 can havea housing wall, e.g., a cylindrical wall, laterally surrounding theelectronics compartment 116. In an embodiment, the housing wall has aninner surface 118 extending around the electronics compartment 116 onthe longitudinal axis 108. The housing wall can include a conductive,biocompatible, inert, and anodically safe material such as titanium,316L stainless steel, or other similar materials, to laterally enclosethe electronics compartment 116. The electronics compartment 116 can beaxially enclosed at a proximal end by the battery 202. Moreparticularly, a distal surface or face of the battery 202 can define theproximal end of the electronics compartment 116. The electronicscomponent 116 can be axially enclosed at a distal end by the headerassembly 110. More particularly, a proximal surface of a feedthroughsubassembly 204 of the header assembly 110 can define the distal end ofthe electronics compartment 116. The housing 102 can be attached, e.g.,welded, to the header assembly 110 and the battery 202. Accordingly, theelectronics compartment 116 can be contained between the battery 202,the inner surface 118 of the housing 102, and the header assembly 110.

In an embodiment, electronic circuitry 206 is contained within theelectronics compartment 116. The electronic circuitry 206 can include aflexible circuit assembly having a flexible substrate. One or moreelectronic components may be mounted on the flexible substrate. Forexample, the electronic circuitry 206 can include one or more passiveelectronic components, e.g., capacitors, and one or more activeelectronic components, e.g., processors. The electronic components canbe interconnected by electrical traces, vias, or other electricalconnectors. In an embodiment, the electronics assembly includes one ormore electrical connectors, e.g., socket and pin connectors ormetallized contact pads, to connect to the battery 202 and theelectrical feedthrough subassembly 204. For example, a socket connectoror a metallized pad can receive and/or connect to an electrode pin, aterminal pin, or an antenna lead, as described below.

To reduce the likelihood that the electrical connectors of theelectronic circuitry 206 might accidentally short-circuit to otherconductive components of the biostimulator 100, such as the housing 102or battery 202, the biostimulator 100 may incorporate components toelectrically insulate and/or protect the electronic components fromshort-circuiting. For example, the biostimulator 100 can include an endinsulator 208. The end insulator 208 can include a planar structureformed from insulating material and sized to separate the electroniccircuitry 206 from the energy source 202. The biostimulator 100 may alsoinclude a wall insulator 210. The wall insulator 210 can be acylindrical sleeve formed from insulating material and sized to separatethe electronic circuitry 206 from the inner surface 118 of the housing102. Accordingly, the end insulator 208 and the wall insulator 210 canshroud the electronic circuitry 206 to reduce the likelihood of shortcircuiting between the electronic components and surrounding structures.It will be appreciated that the flexible substrate of the electroniccircuitry 206 may provide insulation and separation from the housing 102and/or the battery 202. For example, a distal end of the electroniccircuitry 206 may be a fold that is entirely formed from insulatingmaterial, and thus, short circuiting between the distal end and thefeedthrough subassembly 204 can be avoided.

The biostimulator components can form a hermetic enclosure around theelectronic circuitry 206. For example, the battery 202, housing 102, andfeedthrough subassembly 204 can be welded along mating seams at theproximal and distal ends of the housing 102 to hermetically seal theelectronics compartment 116. The feedthrough subassembly 204 can providean isolated electrical path from the electronic circuitry 206, which ishermetically sealed within the electronics compartment 116, to theelectrode 104. More particularly, in an embodiment, the feedthroughsubassembly 204 transmits afferent and efferent signals between theelectronic circuitry 206 and a target tissue.

Referring to FIG. 3 , a perspective view of a feedthrough subassembly ofa header assembly of a biostimulator is shown in accordance with anembodiment. The electrical feedthrough subassembly 204 of the headerassembly 110 can be a multifunction component. Unlike a traditionalpacemaker where the electrical feedthrough is separated from the pacingsite by a lead and functions solely to transfer power to the lead, thedistal electrode 104 of the electrical feedthrough subassembly 204 ofthe biostimulator 100 may be in direct contact with the stimulation siteand used to deliver impulses to the tissue. Additionally, the electricalfeedthrough subassembly 204 can not only serve as the electricalpass-through from a hermetic package to a surrounding environment, butmay also serve other functions, such as providing a housing for asteroid or other filler, or providing direct tissue interaction.

The feedthrough subassembly 204 can include several components havingrespective functions. A flange 302 of the subassembly can be connectedto a case of the biostimulator 100. For example, the flange 302 can bemounted on and bonded to the housing 102 as described above. Thesubassembly can include an insulator 304 to electrically isolate theflange 302 from electrical components passing from the hermeticenclosure of the biostimulator 100 to the surrounding environment. Forexample, the insulator 304 can include and/or be formed from a ceramicmaterial that insulates the flange 302 from the electrode 104. Theelectrode 104 can connect a pulse generator of the electronic circuitry206 to a pacing tip. The flange 302, the insulator 304, and theelectrode 104 can be connected by a brazed joint that hermetically sealsthe components and isolates the pacing tip on a distal end of thesubassembly from a proximal end of the subassembly that connects to theelectronic circuitry 206.

In certain implementations, the electrical feedthrough subassembly 204can be an unfiltered assembly. More particularly, the configuration ofthe electrical feedthrough subassembly 204 can include an activecomponent, e.g., the distal electrode 104, isolated from a groundcomponent (e.g., the flange 302) by the insulator 304. The electrode 104may include the pacing tip, which can include an electrode body 306and/or an electrode tip 308. In implementations of the presentdisclosure, the electrode tip 308 may be mounted on the electrode body306, e.g., on a distal end of the electrode body 306, as illustrated inFIG. 3 . The electrode body 306 and electrode tip 308 can be weldedtogether.

The insulator 304 can surround a portion of the electrode body 306. Moreparticularly, the insulator 304 can contain and separate the conductiveelectrode body 306 from a mounting wall 310 of the flange 302. Both theelectrode body 306 and the mounting wall 310 can be conductive. Bycontrast, the insulator 304 can be formed from an alumina ceramic orother insulating material. Accordingly, the insulator 304 can be locatedbetween the electrode body 306 and the mounting wall 310 to electricallyinsulate the distal electrode 104 from the flange 302. The mounting wall310 can include a thread, e.g., an external thread on an outer surface,which may form a threaded connection between the electrical feedthroughsubassembly 204 and a fixation subassembly of the header assembly 110.The fixation subassembly can include the helix mount 112 and thefixation element 114 mounted on the helix mount 112 (FIG. 1 ). Inimplementations in which the electrical feedthrough subassembly 204 isbonded, press-fit, or otherwise coupled to the helix mount 212, thethread may be omitted or the mounting wall 310 may include other surfacefeatures adapted for coupling the feedthrough subassembly 204 to thefixation subassembly to form the header assembly 110.

Referring to FIG. 4 , an exploded view of a feedthrough subassembly of aheader assembly of a biostimulator is shown in accordance with anembodiment. The flange 302 can include a mounting lip 402 to engage adistal end of the housing 102 (FIG. 1 ). A hermetic weld can be formedaround the mounting lip 402 to seal the electronics compartment 116between the flange 302 and the housing 102. In one implementation, theflange 302 includes a mounting hole 404 that, when the biostimulator 100is assembled, extends distally from the electronics compartment 116along the longitudinal axis 108 and through a distal surface of theflange 302 to a surrounding environment. More particularly, the mountinghole 404 provides a channel between the electronics compartment 116 andthe surrounding environment.

The mounting wall 310 of the flange 302 can extend around the mountinghole 404. In an embodiment, the mounting wall 310 extends around aflange cavity 406 (a distal portion of the mounting hole 404). Forexample, an interior surface 408 of the mounting wall 310 can define theflange cavity 406. The flange cavity 406 can extend through the flange302 from a flange shoulder 410 to a flange distal end 412 of themounting wall 310.

In one implementation and as further illustrated in FIG. 4 , theinsulator 304 for the header assembly 110 of the biostimulator 100 hasan insulator wall 420 extending around an insulator cavity 422. Theinsulator wall 420 can extend longitudinally from an insulator distalend 430 to an insulator proximal end 432. In one implementation, theinsulator wall 420 can be cylindrical, having an outer diameter and aninner diameter; however, other insulator shapes may be used in otherimplementations of the present disclosure. The outer diameter of theinsulator wall 420 can be sized to fit within the mounting hole 404 ofthe flange 208. More particularly, the insulator 304 can be disposedwithin, and can fill, the flange cavity 406 in the assembled state.

In certain implementations, the insulator 304 includes an insulator base424 extending laterally within the insulator cavity 422 at a locationbetween the insulator distal end 430 and the insulator proximal end 432.The insulator base 424 can be a transverse wall extending across theinterior of the insulator 304, orthogonal to the longitudinal axis 108.More particularly, the insulator base 424 can be a transverse wallseparating the insulator cavity 422 of the insulator 304 from a proximalcavity 426 of the insulator 304. The cavities 422, 426 may be radiallyinward from the insulator wall 420. In one implementation, an insulatorhole 428 extends through the insulator base 424 along the longitudinalaxis 108. The insulator hole 428 can interconnect the cavities 422, 426,and the interconnected hole and cavities can provide the insulatorcavity 422 that extends along the longitudinal axis 108 from theinsulator distal end 430 to the insulator proximal end 432. Accordingly,when the insulator 304 is mounted within the flange cavity 406 of theflange 208, and sealed to the flange 208 by a brazed joint, theinsulator cavity 422 provides a channel between the electronicscompartment 116 and the surrounding environment.

In an embodiment, the insulator 304 includes an antenna 434. The antenna434 can be at least partly embedded within the insulator wall 420, asdescribed below. The antenna 434 can be electrically connected tocommunication circuitry of the electronic circuitry 206, and thus,provides wireless communication from the biostimulator 100 to anexternal communication device. The antenna 434 configuration isdescribed further below.

The electrode 104 of the feedthrough subassembly 204 in accordance withthe present disclosure may include a monolithic electrode body 306. Forexample, the monolithic electrode body 306 can have several distinctportions that are integrally formed with each other. In oneimplementation, the electrode body 306 includes a cup 440 and a pin 442that are integrally formed such that the electrode body 306 ismonolithic, or, in other words, has a unitary or single-piececonstruction.

The electrode 104 can be sized to fit within the insulator cavity 422.For example, the pin 442 can be sized to fit through the insulator hole428 of the insulator 304, and the cup 440 can be sized to fit within theinsulator cavity 422 of the insulator 304 (FIG. 5 ). It will beappreciated that, when the electrode 104 is disposed within theinsulator cavity 422, the antenna 434 embedded within the insulator wall420 can extend around the electrode 104. For example, loops of theantenna 434 can extend circumferentially around the cup 440. When theelectrode 104 is disposed within the insulator 304 and the flange 302,and sealed to the insulator 304 by a brazed joint, the monolithicelectrode body 306 provides an electrical pathway from the electronicscompartment 116 to the surrounding environment. Electrical impulses canbe transmitted from the electronic circuitry 206 proximal to theinsulator base 424 to the cup 440 distal to the insulator base 424. Moreparticularly, the cup 440 and the pin 442 can serve as the electricallyactive path from the electronic circuitry 206 within the electronicscompartment 116 to the patient-contacting pacing electrode tip 308.

The biostimulator 100, and more particularly the electrical feedthroughsubassembly 204, can include a filler 450, such as a monolithiccontrolled release device (MCRD). By way of introduction and withoutlimitation, the filler 450 may include a therapeutic material, and canbe loaded into the cup 440. Accordingly, the filler 450 can deliver aspecified dose of a therapeutic agent, e.g., a corticosteroid, intotarget tissue at an implantation site of the biostimulator 100 within apatient. In an embodiment, the filler 450 is retained at a proximallocation within an interior cavity of the cup 440 by a retention spring451. The retention spring 451 can press against a distal end of thefiller 450 and a proximal end of the electrode tip 308 to urge thefiller 450 away from the electrode tip 308 and reduce the likelihood ofthe filler 450 clogging a tip hole 452 of the electrode tip 308.

The electrode tip 308 can be mounted on the electrode body 306 after thefiller 450 is loaded into the cup 440. In one implementation, theelectrode tip 308 includes the tip hole 452 extending through theelectrode tip 308 along the longitudinal axis 108. The tip hole 452 mayprovide a channel between the interior cavity of the cup 440 and thesurrounding environment. Accordingly, therapeutic agent eluted by thefiller 450 can pass through the retention spring 451 and the tip hole452 to the target tissue at the implantation site of the biostimulator100. In other implementations, the electrode tip 308 and/or theelectrode body 306 may include other openings or ports through whichfluid may enter and exit the cup 440. The electrode tip 308 can beconductive, and electrically in contact with the electrode body 306,such that pacing impulses transmitted through the electrode body 306from the electronic circuitry 206 can travel through the electrode tip308 to the target tissue.

In certain implementations, each of the components of the electricalfeedthrough subassembly 204 may be symmetrically formed about thelongitudinal axis 108. For example, the cross-sectional area of theinsulator 304 illustrated in FIG. 4 can be swept about the longitudinalaxis 108 such that the insulator wall 420 has a hollow cylindrical shapeand the insulator base 424 has an annular disc shape. In otherimplementations, the profiles of the one or more of the components ofthe electrical feedthrough subassembly 204 may be non-symmetrical. Forexample, a cross-section of the electrode body 306 taken about atransverse plane extending orthogonal to the longitudinal axis 108 mayreveal an outer surface of the pin 442 and/or the cup 440 that issquare, pentagonal, elliptical, etc., or any other suitable shape.Accordingly, the particular shapes illustrated in the figures areprovided by way of example only and not necessarily by way oflimitation.

Referring to FIG. 5 , a cross-sectional view of a header assembly of abiostimulator is shown in accordance with an embodiment. As describedabove, the housing 102 and a portion of the header assembly 110, e.g.,the flange 302, can define the electronics compartment 116. Theelectronic circuitry 206 can be mounted in the electronics compartment202, and may be in electrical communication with the feedthroughsubassembly 204, e.g., the pin 442, through a socket connector 501 oranother electrical connection.

The header assembly 110 includes the fixation subassembly mounted on thefeedthrough subassembly 204. More particularly, the helix mount 112 canbe mounted on the mounting wall 310 of the flange 302 to connect thesubassemblies and form the header assembly 110. In one implementation,the fixation element 114 includes a helix mounted on the helix mount112. The fixation element 114 can be suitable for attaching thebiostimulator 100 to tissue, such as heart tissue. The helix can extenddistally from the helix mount 112 about the longitudinal axis 108. Forexample, the helix can revolve about the longitudinal axis 108. Thehelix can include a spiral wire, formed by coiling or cut from a wall ofa length of tubing, which extends in a rotational direction around thelongitudinal axis 108. For example, the helix can revolve in aright-handed direction about the longitudinal axis 108. In the case of aright-handed spiral direction, the biostimulator 100 can be advancedinto contact with a target tissue, and the biostimulator 100 can then berotated in the right-handed direction to screw the helix into thetissue. The fixation element 114 may alternatively have a left-handedspiral direction to enable the biostimulator 100 to be screwed into thetarget tissue via left-handed rotation.

In an embodiment, the helix mount 112 may be positioned between thefixation element 114 and the flange 302. The helix mount 112 canelectrically isolate the fixation element 114 from the feedthroughsubassembly 204. For example, the helix mount 112 can be formed from aninsulating material, such as polyetheretherketone (PEEK) to reduce thelikelihood of electrical shorting between the helix 114 and theelectrode 104 or the flange 302. The insulating material of the helixmount 112 may also be rigid to mechanically support the fixation element114 during advancement into the target tissue.

The biostimulator 100 can be implanted in a body region having fluids,e.g., within the blood of a heart chamber, and thus, portions of thebiostimulator 100 can be sealed and/or protected against fluid ingressthat may compromise functionality of the biostimulator 100. For example,portions of the electrical feedthrough subassembly 204, such as theflange 302, may be coated with a protective coating to prevent shortcircuiting of the distal electrode 104 and the proximal electrode 106.In one implementation, the distal electrode 104 is spatially near theflange 302, which can be a portion of the proximal electrode 106. Thus,if blood were allowed to fill the gap between the distal electrode 104and the flange 302, the electrodes 104, 106 could be electricallyshorted and pacing impulses may not properly pace the cardiac tissue.Accordingly, a barrier can be included in the biostimulator 100 toprevent blood from filling a cavity within the biostimulator between thedistal electrode 104 and the proximal electrode 106.

In one implementation, the barrier is provided by a gasket 502. Thegasket 502 can be resiliently compressed between the helix mount 112 andone of the flange 302 (FIG. 5 ) or the insulator 304 (FIG. 7 ). Moreparticularly, the gasket 502 can have an annular body, e.g., an o-ringshape, and the annular body can be resiliently compressed between thehelix mount 112 and either the flange 302 or the insulator 304. Theannular body of the gasket 502 can extend around the electrode 104. Forexample, the annular body can extend circumferentially about the cup440. Accordingly, the gasket 502 can fill a gap between a proximalsurface of the helix mount 112 and a distal face or surface of theelectrical feedthrough subassembly 204. The compressed gasket 502 canform a seal against the compressing surfaces to fill the gap between thedistal electrode 104 and the proximal electrode 106 (e.g., the flange302). Therefore, the gasket 502 can separate and protect the conductivesurfaces of the biostimulator 100 from short circuiting.

Still referring to FIG. 5 , in an embodiment, the gasket 502 isresiliently compressed between the helix mount 112 and the flange 302,and the gasket 502 extends around the insulator wall 420. A radiallyinward surface of the annular body can press against the insulator wall420 to form a seal around the insulator 304. Accordingly, ingress offluid from a gap between the helix mount 112 and the electrode tip 308toward the flange 302 may be prevented.

The antenna 434 can be embedded in the insulator wall 420 as describedabove. The antenna 434 may have one or more antenna loops 504 locatedwithin the insulator wall 420 between the insulator distal end 430 andthe insulator proximal end 432. The dielectric constant of the ceramicmaterial surrounding the metallic antenna loops 504 can allow theantenna 434 to be much smaller than the typical ribbon antennas used inconventional pacemakers. Accordingly, the antenna 434 can occupy minimalspace, and does not require an increase in the overall device size.

In an embodiment, the antenna loop(s) extend around the longitudinalaxis 108. For example, the one or more loops may include several loopsextending circumferentially around the electrode 104 disposed within theinsulator cavity 422. In any case, the loops may have a circular patternwithin respective transverse planes oriented perpendicular to thelongitudinal axis 108.

The one or more antenna loops 504 can be embedded in the insulator wall420 distal to the flange distal end 412. More particularly, theinsulator distal end 430 can be distal to the flange distal end 412, andthe antenna loops 504 can be located longitudinally between theinsulator distal end 430 and the flange distal end 412. It will beappreciated that locating the antenna loops 504 distal to, e.g.,vertically above, the flange distal end 412 can reduce interference fromthe metallic mounting wall 310, and accordingly, may optimize acommunication range of the antenna 434.

The antenna 434 can include an antenna lead 506 extending longitudinallyfrom the antenna loops 504. In an embodiment, the antenna lead 506 isconnected to a lower antenna loop at a distal end and extends from thelower antenna loop along a lead axis 508. The lead axis 508 can extendlongitudinally, e.g., parallel to the longitudinal axis 108.Accordingly, the antenna lead 506 can extend through the insulator wall420 and outward from the insulator proximal end 432. In an embodiment,the antenna lead 506 extends into the electronics compartment 116 andelectrically connects to electronic circuitry 206 contained within theelectronics compartment 116. Accordingly, communication circuitry canuse the antenna 434 to communicate wirelessly with an externalcommunication device.

In addition to the antenna lead 506, the antenna 434 can includeelectrical connectors to interconnect the various antenna components.For example, the lower antenna loop can be connected to an adjacent (oran upper) antenna loop through an antenna via 510. The antenna via 510can extend vertically to interconnect the stacked loops. Alternativeelectrical connectors to interconnect the various antenna components caninclude lateral traces (FIG. 7 ).

Referring to FIG. 6 , a perspective view of an insulator for a headerassembly of a biostimulator is shown in accordance with an embodiment.The insulator 304 is shown in dashed lines to improve visibility of theembedded antenna 434. The antenna 434 may be a monopole antenna. Moreparticularly, the one or more antenna loops 504 can include one or moreopen loops 602. The open loops 602 can be c-shaped and extend fromrespective first ends 604 to respective second ends 606. The first endscan be connected to the antenna lead 506 (or to the antenna via 510). Bycontrast, the second ends 606 can be free ends. The c-shaped profile ofthe open loops 602 may have a width dimension that is greater than awidth of the insulator cavity 422 and less than a width of the insulatorwall 420. More particularly, the open loops 602 may be fully embeddedwithin the insulator wall 420. Alternatively, a portion of the antennaloops 504 may be exposed from the insulator wall 420. For example, thefirst ends 604 may be exposed and the second ends 606 may be embedded.

The first end 604 and the second end 606 of each loop 504 can be withina same transverse plane. More particularly, the loops may behorizontally configured and vertically stacked. The horizontalorientation of the antenna loop 504 provides for the loop profile to beperpendicular to the lead axis 508. Accordingly, the antenna lead 506can intersect and extend perpendicular to the antenna loops 504. Theantenna lead 506 can be coaxial with, or laterally offset from, theantenna via 510. The lead and the via may be embedded or exposed fromthe insulator wall 420. As shown, the lead 506 can extend from the loopsto a free end 610 that is exposed below the insulator wall 420. Moreparticularly, the free end 610 may be proximal to the insulator proximalend 432. The free end 610 can connect to the electronic circuitry 206.

Referring to FIG. 7 , a cross-sectional view of a header assembly of abiostimulator is shown in accordance with an embodiment. The headerassembly 110 of FIG. 7 can have similar or identical components andfeatures to the header assembly 110 of FIG. 5 . In an embodiment,however, rather than being located external to the insulator 304, thegasket 502 can be located internal to the insulator 304. The gasket 502can therefore be resiliently compressed between the helix mount 112 andthe insulator 304 to seal against the ingress of fluid toward the flange302. Furthermore, the gasket 502 may extend around the electrode 104,and thus, the gasket 502 may be resiliently compressed between the helixmount 112 and the electrode 104.

In an embodiment, the insulator cavity 422 includes a counterbore 702.For example, the insulator 304 can have a distal section 704 and aproximal section 706, and the counterbore 702 can be in the distalsection 704. The counterbore 702 can be a flat-bottomed hole, and thebottom of the counterbore 702 can be a top surface of the insulator wall420 extending over the proximal section 706. The gasket 502 may bedisposed within the counterbore 702. The gasket 502 can be compressedvertically between a bottom surface of the helix mount 112 and the topsurface of the proximal section 706 of the insulator wall 420. Thecompressed gasket 502 within the counterbore 702 ensures electricalisolation between the tip electrode 104 and the flange 302.

The antenna 434 can be embedded within the distal section 704 of theinsulator wall 420. As described above, the distal section 704containing the antenna 434 can protrude out of the flange 302 such thatthe antenna loops 504 are positioned for optimal communication range.Furthermore, since the distal section 704 can extend radially outwardfrom the proximal section 706, the antenna loops 504 may be verticallyabove the mounting wall 310. Accordingly, the antenna loops 504 of theembodiment illustrated in FIG. 7 may be wider than the antenna loops 504of the embodiment illustrated in FIG. 5 .

Whereas the antenna loops 504 may be embedded within the wider distalsection 704 of the insulator wall 420, the antenna lead 506 may beembedded within the narrower proximal section 706 of the insulator wall420. As such, the antenna lead 506 may be radially inward from theantenna loops 504, and accordingly, the lead axis 508 can extendlongitudinally through (radially inward of) the one or more loops. Forexample, the lead axis 508 can extend perpendicular to the transverseplanes containing the antenna loops 504 and through the areas containedby the antenna loops 504 within the transverse planes. The antenna lead506 can extend through a length of the insulator 304 to the electroniccircuitry 206 contained within the electronics compartment 116.

The antenna loops 504 can include several stacked loops, as describedabove, and the loops can be interconnected by the antenna via 510.Similarly, the lower antenna loop 504 can be connected to a distal endof the antenna lead 506 by a lateral trace 708. More particularly, thelateral trace 708 can extend transversely inward from the lower antennaloop 504 to the antenna lead 506.

Referring to FIG. 8 , a perspective view of an insulator for a headerassembly of a biostimulator is shown in accordance with an embodiment.As described above, the insulator wall 420 includes the distal section704 having a first transverse width 802 larger than a second transversewidth 804 of the proximal section 706 of the insulator wall 420. Theantenna loops 504 embedded in the wider distal section 704 can be openloops 602 to provide a monopole antenna 434. The open loops 602 can beconnected to the antenna lead 506, which is embedded within the narrowerproximal section 706. A lateral trace 708 can extend laterally from theloops to the lead to interconnect the components. Thus, the antennaloops 504 can be mounted above the mounting wall 310, and the antennalead 506 can extend through the flange cavity 406 parallel to the pin442 that carries electrical impulses to and from the electroniccircuitry 206. Accordingly, communication signals and pacing impulsescan be simultaneously transmitted from the electronic circuitry 206 tolocations distal to the flange 302 through the electrical feedthroughsubassembly 204.

In the foregoing specification, the invention has been described withreference to specific exemplary embodiments thereof. It will be evidentthat various modifications may be made thereto without departing fromthe broader spirit and scope of the invention as set forth in thefollowing claims. The specification and drawings are, accordingly, to beregarded in an illustrative sense rather than a restrictive sense.

What is claimed is:
 1. An insulator for a header assembly of abiostimulator, comprising: an insulator wall extending around aninsulator cavity, wherein the insulator cavity extends along alongitudinal axis from an insulator distal end of the insulator wall toan insulator proximal end of the insulator wall; and an antennaincluding one or more antenna loops embedded in the insulator wallbetween the insulator distal end and the insulator proximal end, and anantenna lead extending from the one or more antenna loops through theinsulator proximal end to a free lead end.
 2. The insulator of claim 1,wherein the insulator includes a ceramic material.
 3. The insulator ofclaim 1, wherein the one or more antenna loops include one or more openloops having respective free loop ends.
 4. The insulator of claim 3,wherein the one or more open loops include a plurality of open loopsextending around the longitudinal axis.
 5. The insulator of claim 3,wherein the antenna lead has a lead axis extending longitudinallythrough the one or more antenna loops, and wherein a lateral traceextends transversely inward from the one or more antenna loops to theantenna lead.
 6. The insulator of claim 1, wherein a distal section ofthe insulator wall has a first transverse width larger than a secondtransverse width of a proximal section of the insulator wall.
 7. Aheader assembly for a biostimulator, comprising: a flange including amounting wall extending around a flange cavity, wherein the mountingwall has a flange distal end; and an insulator within the flange cavityand including an insulator wall extending around an insulator cavity,wherein the insulator cavity extends along a longitudinal axis from aninsulator distal end of the insulator wall to an insulator proximal endof the insulator wall, and an antenna including one or more antennaloops embedded in the insulator wall distal to the flange distal end,and an antenna lead extending from the one or more antenna loops throughthe insulator proximal end to a free lead end.
 8. The header assembly ofclaim 7 further comprising an electrode within the insulator cavity,wherein the one or more antenna loops extend around the electrode. 9.The header assembly of claim 8 further comprising: a helix mount mountedon the flange; and a gasket having an annular body extending around theelectrode, wherein the annular body is resiliently compressed betweenthe helix mount and one of the flange or the insulator.
 10. The headerassembly of claim 9, wherein the gasket is resiliently compressedbetween the helix mount and the flange, and wherein the annular bodyextends around the insulator wall.
 11. The header assembly of claim 9,wherein a distal section of the insulator wall has a first transversewidth larger than a second transverse width of a proximal section of theinsulator wall, and wherein the gasket is resiliently compressed betweenthe helix mount and the insulator.
 12. The header assembly of claim 11,wherein the insulator cavity includes a counterbore in the distalsection, and wherein the gasket is disposed within the counterbore. 13.A biostimulator, comprising: a housing having an electronicscompartment; a flange mounted on the housing and including a mountingwall extending around a flange cavity; and an insulator within theflange cavity and including an insulator wall extending around aninsulator cavity, wherein the insulator cavity extends along alongitudinal axis from an insulator distal end of the insulator wall toan insulator proximal end of the insulator wall, and an antennaincluding one or more antenna loops embedded in the insulator wallbetween the insulator distal end and the insulator proximal end, and anantenna lead extending from the one or more antenna loops through theinsulator proximal end to a free lead end.
 14. The biostimulator ofclaim 13, wherein the one or more antenna loops include a plurality ofopen loops extending around the longitudinal axis.
 15. The biostimulatorof claim 14, wherein the antenna lead has a lead axis extendinglongitudinally through the one or more antenna loops, and wherein alateral trace extends transversely inward from the one or more antennaloops to the antenna lead.
 16. The biostimulator of claim 13 furthercomprising an electrode within the insulator cavity, wherein the one ormore antenna loops extend around the electrode.
 17. The biostimulator ofclaim 16 further comprising: a helix mount mounted on the flange; and agasket having an annular body extending around the electrode, whereinthe annular body is resiliently compressed between the helix mount andone of the flange or the insulator.
 18. The biostimulator of claim 17,wherein a distal section of the insulator wall has a first transversewidth larger than a second transverse width of a proximal section of theinsulator wall.
 19. The biostimulator of claim 18, wherein the insulatorcavity includes a counterbore in the distal section, and wherein thegasket is disposed within the counterbore.
 20. The biostimulator ofclaim 13, wherein the antenna lead is electrically connected toelectronic circuitry contained within the electronics compartment.